Muffler



Oct. 1 1935. Q. G. NoBLlTT ET AL MUFFLER 2 Sheets-Sheet l Filed Aug. 3, 1951 Wwwf m www a wld 0 M00@ /W m/ N TLU www @E Oct. 1, 1935. Q G, NOBLlT-r ET AL 2,016,254

MUFFLER Filed Aug. 3, 1931 2 sheets-fsheet 2 Aw x; 'W 'kg l l l .l K y g l l N N n I N l l I Emil. C can-H nrw u l l @e in gg fpm/N LupLow; K f l y dummy.'

Patented Oct. 1, 1935;

PATEN'IA OFFICE 2,016,254 MUFFLER Quintin G. Noblitt, Earl C. Booth, and Edmund Ludlow, Indianapolis, Ind, assignors to Noblltt- Sparks Industries, Inc., Indianapolis, Ind., a

corporation of Indiana Application August 3, 193i, serial No. 554,723

' 6 Claims.

Our invention is concerned with muiiiers or sllencers for use in silencing the noises made by flowing gases, and particularly with muiilers for use in silencing the exhaust from internal combustion engines. It is the object of our invention to produce a muiiler which may be simply and economically constructed, which will be light in weight, which will be compact, and which will adequately silence the noises resulting from gas ilow, While creating a back-pressure much smaller than that created by many mufllers ,in common use.

In carrying out our invention we provide a hollowcasing through which there extends a plurality of gas-passages each of which communicates with an inlet opening at one end of the casing and an outlet opening at the other. Conveniently, the gas passages are displaced at angularly spaced points around the inner side of the casing, with the casing wall serving to deiine a portion of each gas-passage. Each of the gas passages is provided at a plurality of points along its length with openings each affording restricted communication between the interior of such passage and the surrounding space within the casing; and the space within the casing and outside the gas passages is divided into sections by one or more partitions which prevent unobstructed flow ofgases from one end of the casing to the other outside the gas passages.

The accompanying drawings illustrate mutliers embodying our invention: Fig. 1 is a longitudinal section through one form of muiier on the line. I-I of Fig. 4; Fig. 2 is an isometric view of a distributor plate by which the gases are divided among the several gas-passages; Fig. 3 is an isometric vlew illustrating one of the partitions with fragments of the gas-passages; Fig. 4 is a transverse section on the line 4-4 of Fig. 1; Fig. 5 is a. longitudinal section, on the line 5--5 of Flg. 6. showing a modified form of gas-passage; Fig. 6 is a transverse section of the mufller illustrated in Fig. 5; Fig. '7 is a fragmental plan, in partial section, of one of the gas passages tFig. 8 is a section 4on the line 8-8iof Fig. 7; and Figs. 9 and 10 are may be provided on the heads I2 to facilitate the connection .of the muiller to an exhaust pipe and a. tail-pipe.

Within the muiiler, as previously indicated, we provide a plurality of gas-passages. [As is clear 5 from the drawings, we prefer to form these gas passages by means of sheet-metal stampings I5 each of which is' generally semicircular in crosssection and is provided along its longitudinal edges with flanges I6 adapted to be secured 1o against the inner face of the casing I0 as by means of spot-welding. At a plurality of points along the length of each of the passages I5, openings Il are provided for the purpose of aflording communication between the interior ofthe pas'- sage and the interior of the casing I0. We prefer to provide these openings by cutting transverse slits through the wall of the passage and by displacing, either inwardly or outwardly the metal at one side of each of such slits to form louvers I 8. 20 As shown inthe drawings, these slits are disposed in pairs, the two slits of each pair lying in the same transverse plane and being separated by a strengthening rib I5 struck up from the sheetmetal stamping in the formation thereof.

At each end of the casing, and within the adjacent head I 2, there is located a distributing plate 20 having near its margin angularly spaced semicircular holes 2I adapted to register respectively with the ends of the passages I5. The central portion of each plate 20 is displaced outwardly to form a projecting boss, the sides of which in alinement with each of the openings 2l are displaced inwardly to form grooves which direct the gases to or from the adjacent openings of the passage I5. The distributing plates close the space within the' muffler and outside the `gas--passages and insure that substantially all gases entering or leaving the muffler body pas's through the gas-passages I5.

Conveniently', each end of the casing IIJ is 4o flanged outwardly, the periphery of the adjacent distributing plate 20 lying against such ilange and the edge of the head I2 being crimped around the edges of the distributing plate and casingiiange to secure ythe distributing plate and head 45 in position.

Within the casing, we may provide one or more transverse partitions 25 adapted to divide the interior of the casing into a plurality of chambers. These partitions 25 fit comparatively closely 50 about the passages I5, but itis not essential that they prevent all gas-ilow between adjacent chambers.

In operation, one end of the casing is connected to receive exhaust gases from the engine. Such gases. entering the head I2, impinge upon the distributing plate III and are directed toward the longitudinal gas-passages I5 through which they flow to the opposite end of the muiiler where they g are discharged. The gas-passages I5 are preferably unobstructed, and the openings Il in the walls of the passages I5 permit the gases to flow back and forth between the interior of each passags and the interior of the casing under the innuance of local and transient pressure conditions. Each of the partitions tends to insure that gases which pass from the interior of any passage I5 to the interior of the casing return to one or the other of the passages before nowing into 1l me next section of the mufiier.

It will be noted that by reason ofthe manner in which the openings in the walls of the passages Il are formed the dow of gases through auch openings will occur more readilyin one diso reotion than in the other. Thus, assuming the general direction of gas flow through the muiiler to be from left to right in Fig. 1, gases will flow more readily ln an outward than in an inward dilection through the openings in the upper and 8l center passages. but will flow more readily inwadly through the openings in the lower passage. mis is so because of the inclination of the louvers which are so arranged, as shown, to tend to facilitate outward flow of the gases as they pass to the 50 right in the upper and center tubes but to facilitate inward flow of gases as they pass to the right through and in the vicinity of the lower tube.

` As indicated incur co-pending application Serial No. 554,722, filed August 3, 1931, which shows 85 a related mumer and contains claims broadly coverin; the specific mufner herein described, we have pointed out that advantages result from sloping some of the louvers is inwardly and others outwardly. This result may be accomlil` pllshed in the manner already described-that is, by forming all the louvers on each gas passage j jlwith the same slope and disposing one of the passo that its louversslope oppositely to those iof other passages. In the modification of our `invention illustrated in Fig. 5, the same result is accomplished by forming each stamping I5 so that the louvers on one sideof its longitudinal center slope in one direction while those on the `other side slope in the opposite direction. Prefstably. the louvers are arranged to slope outwardly `in a direction away from the ends of the pasngermer-elly gases entering the munier will be biased outward now while those near the discharge end of the mumer will be biased toward in- 58 ward flow. as the result of the direction in which the louvers slope.

, Preferably, although not necessarily, each of the stampings Il is formed, in the vicinity of each er the parutions u, as indicated in Figs. '1 and a.

U "That is, one of the louvers Il adjacent the partition 25 is made of somewhat greater axial length than the other louvers and is formed to provide a cylindrical portion Il having a diameter approximately um to that of the opening in the '5 parution n. .rust beyond the cylindrical portion the casing III into three portions each of which contains one of the gas-passages I5.

As pointed out in our co-pending application above referred to, the silencing efliciency of a muilier depends upon a large number of factors 5 4inadequate silencing, the degree of silencing produced can be increased by increasing the number of the partitions 25. There is a limit, largely determined by considerations of cost, to' the number of partitions which can be used in a muliler; go and if the desired degree of silencing has not been obtained by increasing the number of partitions to that limit, it may be increased by increasing the size of the muiiier.

As a specific example of a mufiier for use with g5 a particular engine, we might state that, for the six-cylinder, 205 cubic inch engine of the Studebaker automobile a muiller having a casing-body 20 inches in length and flve inches in diameter with three of the gas-passages I5 each one and 30 one-half inches in diameter proved satisfactory. In this muilier, there were two transverse baiiies 25, the slots I1 were spaced one-half inch apart, and the louvers were displaced outwardly sumciently far to make the slots I1 about 0.020 in 35 0.025 inch in width. While a one-half inch spacing of the slots I1 is generally satisfactory,

a closer spacing, of three-eights or one-quarter of an inch, will increase the silencing eillclency somewhat. The width of the slots is of como paratively slight importance and may be varied considerably without noticeably influencing the silencing action of the muffler. Slots narrower than 0.010 inch, while satisfactory from a silencing standpoint, are apt to become clogged, while the silencing action begins to suffer if the slots are increased in width much beyond 0.040 inch.

To avoid the creation of excessive back pressure, the total cross-sectional area of all the gas- 50 passages I5 should not be materially less than the cross-sectional area of the exhaust pipe through which gases are supplied to the muffler.

It will be noted that in all the muiilers described the gas passages are unobstructed, and the bulk of the gases may therefore flow freely from the inlet opening to the discharge opening of the muflier. Because of this, the back-pressure which the mufiier ofl'ers to the flow of gases is extremely small compared to that developed by most other muillers in common use. Because of the simple arrangement ofparts, which lends itself to sheet-metal construction, the muiiier may be very economically manufactured and is light in weight. Further, I have found that by dividing the exhaust gases and causing them to flow in parallel through several silencing gaspassages, the over-all length of a muiiler of given silencing efficiency may be materially reduced We claim as our invention:

1. A silencer for gases, comprising a. hollow casing having inlet and discharge openings, a plurality of gas passages disposed within said casing and affording communication between said inlet and discharge openings, each of said passages being formed by a trough-shaped member secured to said casing with its open side adjacent the inner surface of the casing, said members being provided with louvers some of which slope in one direction and others of which slope in the opposite direction.

2. A silencer as set forth in claim 1 with the addition that the louvers on each member al1 slope in the same direction, at least one of said members being disposed so that its louvers slope in a direction opposite to those of the other member or members.

3. A silencer for gases, comprising a hollow casing having inlet and discharge openings, a plurality of gas passages disposed within said casing and affording communication between said inlet and discharge openings, each of said passages being formed by a trough-shaped member secured to said casing with its open side adjacent the inner surface of lthe casing, each of said members being provided on both sides of its longitudinal center with louvers sloping outwardly toward the longitudinal center of e the member.

4. A silencer for gases, comprising a hollow casing having inlet and discharge openings, a plurality of gas passages disposed within said casing and affording communication between said inlet and discharge openings, each of said passages being formed by a trough-shaped memof said trough-shaped members being provided at a multiplicity of points along its length with openings providing restricted communication between its interior and said chamber, transverse partitions disposed within said casing adjacent the ends of said trough-shaped members and closing the ends of said chambers, and one or more auxiliary transverse partitions extending across said chamber between the ends thereof.

5. A silencer for gases, comprising a hollow 10 casing having inlet and discharge openings, a plurality of .gas passages disposed within4 said casing and affording communication between said inlet and discharge openings. each of said passages being formed by a trough-shaped mem- 15 ber secured to said casing with its open side adjacent the inner surface of the casing, said trough-shaped members and casing being arranged to provide a chamber within the casing and between the trough-shaped members, each 20 of said trough-shaped members being provided at a multiplicity of points along its length with openings providing restricted communication between its interior and said chamber, and transverse partitions disposed within said casing ad- 25 

